This invention relates to apparatus for handling a tube of flexible plasticsmaterial cut from a web of that material. The invention further relates to a method of handling such a tube, for the further processing thereof.
The apparatus and method of this invention are particularly concerned with the manufacture of container liners and will in the following be described essentially solely in relation to that manufacturing process. It is however to be understood that the invention is not limited to that manufacturing process and aspects of the apparatus and method may equally be used in other processes.
Liners for cargo containers, such as ISO box containers, are well-known and widely used for the bulk transport of flowable productsxe2x80x94for example granular materials including agricultural produce and chemicals. Such liners are usually made from plastics sheet material which is pre-formed into a tube, or from sheet material which is suitably folded and subsequently is seam-welded to make a tube. End panels for a liner are provided either by welding the plastics material in an appropriate manner or by bonding into the tube a separate end panel. Access openings are provided both for the loading and discharge of the liner, when in use, and such openings frequently are fitted with access pipesxe2x80x94for example for the introduction of the product into the liner. Further, suitable arrangements must be made for the suspension of the liner in a container.
The manufacture of such a container liner tends to be somewhat labour intensive. Typically, a web of the plastics material is supported adjacent a work-table and is drawn out over that work-table so that the required operations may be performed by operators reaching across the liner and using suitable tools, such as thermal welding apparatus. In view of the width of such a liner, these operations are not very easy to perform in the central region of the liner where, for example an access pipe must be bonded to the liner, around an access opening formed through the material of the liner. A high degree of skill is required to ensure the bonding process, such as thermal welding, is carried out efficiently to provide a reliable joint which will not fail in use.
The present invention stems from research into ways for facilitating the handling of a plastics material tube which is to form the access pipe of a completed liner, and so which must be cut from a web of flexible plastics material and then bonded to a liner, around an opening pre-formed therein. The access pipe may be made of relatively thin-wall plastics material and so is not self-supporting; this leads to particular difficulties in handling the tube both at the time of cutting a suitable length from the web and subsequently to shape and bond the tube to the liner, to form the access pipe.
According to one aspect of the present invention, there is therefore provided apparatus for handling a tube of flexible plastics material drawn and then cut from a web thereof, which apparatus comprises a disc-shaped support having a greater diameter than the internal diameter of the tube and over which the material is drawn, and a carrier for the support, in which apparatus the support is mounted on the carrier for movement between a first position where the support lies at an angle to a radial plane of the tube to permit drawing of the tube thereover and a second position where the support lies substantially in a radial plane of the tube so that the part of the tube in which is located the support is stretched over the support and so is held thereby.
According to a second and closely related aspect of the present invention, there is provided a method of handling a tube of flexible plastics material using a disc-shaped support having a greater diameter than the internal diameter of the tube when opened out and being adjustably mounted on a carrier for movement between a first position where the support lies at an angle to a radial plane of the tube and a second position where the support lies substantially in a radial plane of the tube, in which method the support is disposed at its first position, a length of the tube is drawn over the support from a web thereof, the support is moved to its second position so that the part of the tube in which is located the support is stretched over the support and so is held thereby, and the drawn length of the tube is cut from the web, adjacent the support.
By using the apparatus of this invention, or performing the method of this invention, it becomes possible to handle on an automated basis a tube of relatively flexible, or xe2x80x9cfloppyxe2x80x9d, plastics material to form an access pipe for a container liner. Despite the nature of the plastics material, a required length of the tube may be cut from the web and then be transferred to a bonding station where the tube is bonded to the material of the liner, around an opening pre-formed in the liner, without the need for intervening manual operations.
The handling of the floppy tube is possible in view of the movement of the support between its first and second positionsxe2x80x94the support should have an effective projected area of no greater than the area of the tube (when opened out into a circular shape) when the support is in its first position, but has an effective area greater than the area of the tube when the support is in its second position. Thus, the material may be drawn over the support relatively easily so as to have the support positioned within the tube adjacent one end thereof, when the support is in its first position, but the tube is held firmly, in its opened-out configuration, when the support is in its second position.
Preferably, the support is moveable to a third position inclined at an angle to the radial plane of the tube and beyond the second position with respect to the first position. In this case, the movement of the support from the first position may go through the second position to the third position before finally returning to the second position. Such xe2x80x9cover-runningxe2x80x9d of the support by a few degrees ensures that the material of the tube is not unduly stretched locally when the support finally is in its second position, and that the support is properly located in the tube, in a radial plane, at the time the tube is cut from the web.
Conveniently, the carrier is mounted on a sub-frame, arranged for movement of the support from a loading position where the tube is drawn over the support, to a discharge position where a cut length of tube is subjected to a further processing stepxe2x80x94for example, the cut length is bonded to a container liner under manufacture.
The support itself may be in two parts, having an auxiliary disc connectable co-axially to the support and selectively releasable therefrom. For example, an electromagnet mounted on the support or auxiliary disc may be provided to allow such connection and release. The auxiliary disc preferably has a diameter no greater than that of the support, but may be smaller. In the latter case, it is advantageous for the area of the auxiliary disc to be substantially the same as that of the tube, when opened out.
The tube cutter preferably acts on the tube at a position adjacent the support when in its second position. Such a tube cutter may comprise at least one blade arranged for rotational movement about the tube, so as to effect a circumferential cut through the tube. For a two part support, the cutter preferably acts to cut the tube between the two parts. Either an externally-acting cutter or a cutter arranged between the two parts of the support, to act internally of the tube, may be employed.
A gripper mechanism may be mounted for vertical movement on the carrier, which gripper mechanism is arranged for gripping an end portion of the tube and then to draw the tube over the support prior to the cutting of the tube. Such a gripper mechanism may have an annulus surrounding the support and provided with gripping fingers or other clamps, to grasp the end portion of the tube.